JP2796023B2 - Combustion control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combustion control device for performing feedback control of fuel combustion in an internal combustion engine such as an automobile engine.

[0002]

2. Description of the Related Art A zirconia oxygen sensor is widely used as a sensor for detecting an air-fuel ratio in a combustion control device for performing feedback control of fuel combustion in an internal combustion engine. However, this sensor has a long response time,
There was a problem in controllability in the transient operation state. Therefore,
2. Description of the Related Art An optical combustion control device that determines an air-fuel ratio from light emitted from combustion gas and performs feedback control of combustion has been proposed.

FIG. 3 is a sectional view showing a light detecting section of a conventional optical combustion control device described in Japanese Patent Application Laid-Open No. 57-186040. In the figure, 3 is a spark plug, 4 is an external electrode provided at the tip of the spark plug 3, and 5 is an external electrode 4.
The central electrode 10 of the ignition plug 3 provided opposite the light source 10 is a light inlet provided in the ignition plug 3, and the reference numeral 21 a is a red light installed in the ignition plug 3 behind the light inlet 10. The photosensitive diode 21b is a blue light-sensitive diode similarly installed behind the light inlet 10.

Next, the operation of the above-described conventional combustion control device will be described. During the expansion stroke of the internal combustion engine, light is emitted as the fuel burns in the combustion chamber, and the light is
The light is guided to the light inlet 10 through the space around the center electrode 5 and reaches the red light sensitive diode 21a and the blue light photosensitive diode 21b. At the time of this light emission, when the air-fuel ratio of the air-fuel mixture is darker than the stoichiometric air-fuel ratio, the color of the flame becomes red, and when it is light, it becomes blue. Therefore, during combustion,
By comparing the outputs of the red light sensitive diode 21a and the blue light photosensitive diode 21b, it is possible to determine whether the air-fuel ratio deviates from the stoichiometric air-fuel ratio in a darker direction or a thinner direction. . If the fuel injection amount is feedback-controlled based on this determination, the air-fuel ratio can be controlled to an optimum value with good responsiveness even during transient operation of the vehicle.

[0005]

Since the conventional optical combustion control device is configured as described above, it is effective only for air-fuel ratio control. However, with the tightening of exhaust gas regulations, When fine control such as EGR control, ignition timing control and secondary air control is required,
There is a problem that the information amount is too small from only the outputs of the two photosensitive diodes, so that appropriate control cannot be performed. Therefore, means for detecting the concentration of each component such as oxygen, nitrogen oxides, carbon monoxide, and hydrocarbons in exhaust gas has been desired.

In another conventional optical combustion control device, a method of guiding light generated by fuel combustion to a spectrophotometer and performing spectrum analysis to obtain a concentration for each component has been studied. In order to perform spectral analysis, it is necessary to stop the light once with a narrow slit, and to detect only light of a specific spectrum after being dispersed by a prism or diffraction grating, so that a very strong light is guided to the spectrophotometer. I need to do it. For this reason, a lens for condensing light,
An optical device such as a reflecting mirror tends to be large, and has not been put to practical use.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and it is possible to detect the concentration of a plurality of components in a combustion gas or an exhaust gas with a simple device and perform fine combustion control. The aim is to obtain a possible combustion control device.

[0008]

According to a first aspect of the present invention, there is provided a combustion control device which penetrates a center electrode of an ignition plug of an internal combustion engine and is provided in a gap between the external electrode of the ignition plug and the center electrode. It has a light inlet, and from this light inlet,
An optical fiber that guides spark light generated at the time of ignition of the ignition plug, a spectrophotometer connected to the optical fiber, and a gas composition is analyzed from an output of the spectrophotometer to feed back fuel combustion in the internal combustion engine. A control circuit for controlling the ignition circuit and a ignition circuit for supplying a high voltage to the ignition plug.
During the expansion stroke, except during normal ignition timing.
Also during the exhaust stroke, the ignition circuit
A spark is generated and the composition of the gas is analyzed.
Feedback control of fuel combustion in
It is a thing.

[0010]

According to the first aspect of the present invention, there is provided a combustion control device comprising:
Since the spark light of the spark plug of the internal combustion engine is collected from the center of the spark, strong light can be guided to the spectrophotometer with a simple device.

[0011] Also, the spark is normal and in the non-ignition timing example the exhaust stroke, since it is also possible to generate during the expansion stroke, it is possible to know the concentration of each gas component in their stroke, more Fine combustion control can be performed.

[0012]

[Embodiment 1] Hereinafter, a combustion control device according to an embodiment of the present invention will be described with reference to the drawings. In FIG. 1, 1 is a combustion chamber of an internal combustion engine (not shown), 2 is a cylinder head of a cylinder that forms the combustion chamber 1, 3 is a spark plug attached to the cylinder head 2, 4 is an external electrode of the ignition plug 3, Reference numeral 5 denotes a central electrode of the ignition plug 3, reference numeral 6 denotes an ignition circuit for supplying a high voltage to the ignition plug 3, reference numeral 7 denotes a high tension cord connecting the ignition circuit 6 and the ignition plug 3, and reference numeral 8 denotes a high tension cord 7 attached to the end of the high tension cord 7. A socket 9 of the ignition plug 3, an optical fiber penetrating on the central axis of the center electrode 5 of the ignition plug 3, and having a light inlet 10 in a gap between the external electrode 4 and the center electrode 5, 11 is a spectrophotometer , 12 have one end connected to the optical fiber 9 by an optical connector described later, and the other end connected to the spectrophotometer light 11.
An optical fiber for guiding the spark light guided by the light to the spectrophotometer 11;
An optical connector 14 for connecting the optical fiber 12 and the optical fiber 12 is a control circuit to which the output of the spectrophotometer 11 is input and controls the fuel combustion of the internal combustion engine. In the first embodiment, the optical fiber for guiding the spark light to the spectrophotometer 11 is composed of two optical fibers, the optical fiber 9 and the optical fiber 12, but these are composed of one optical fiber. May be.

The operation of the first embodiment will be described below. In the internal combustion engine, a high voltage is sent from the ignition circuit 6 to the ignition plug 3 through the high tension cord 7 shortly before the end of the compression stroke, and is generated in a gap between the external electrode 4 and the center electrode 5 of the ignition plug 3. The mixture in the combustion chamber 1 is ignited by the spark. The spark light generated at this time passes through the light inlet 10 and the optical fibers 9 and 12, and the spectrophotometer 1
It is led to 1. The output of the spectrophotometer 11 is read into the control circuit 14 in accordance with the spark generation timing.
Since the spark light has a spectrum distribution specific to the gas composition at the time of spark generation, the control circuit 14 analyzes the combustion state based on the gas composition obtained from this spectrum, and feeds back the fuel combustion in the internal combustion engine. Can be controlled.

In the above description , the spark light at the normal ignition timing is used. However, in addition to the normal timing, a spark may be generated during the expansion stroke or the exhaust stroke to analyze the gas composition. , It is possible to know the composition of the gas during each step. In particular, in an internal combustion engine such as a four-cycle engine, in order to partially simplify the configuration of the ignition device,
It is easy to generate a spark during the exhaust stroke, such that some air-fuel mixtures ignite at a 360 ° angle from the normal ignition timing during the exhaust stroke, even at unnecessary times. Oxygen, nitrogen oxides during the exhaust stroke,
Knowing the concentration of each component such as carbon monoxide and hydrocarbons is particularly important for exhaust gas control, and based on this information, the fuel injection amount, injection timing, ignition timing, EG
By performing feedback control such as R and secondary air, cleaner exhaust gas can be realized.

Embodiment 2 FIG. In the first embodiment, the end of the optical fiber 9 is used as the light inlet 10 as it is. However, as shown in FIG.
0 may be provided with a condenser lens 20. By providing the condenser lens 20, intense light can be guided to the spectrophotometer 11, and the surface area of the light inlet 10 is increased, so that the spectrophotometer 11 is resistant to dirt.

[0016]

As described above, the combustion control apparatus according to the first aspect of the present invention penetrates the center electrode of the ignition plug of the internal combustion engine, and provides a gap between the external electrode of the ignition plug and the center electrode. Has a light inlet, from this light inlet,
An optical fiber that guides spark light generated at the time of ignition of the ignition plug, a spectrophotometer connected to the optical fiber, and a gas composition is analyzed from an output of the spectrophotometer to feed back fuel combustion in the internal combustion engine. Since a control circuit for controlling the light source is provided, it is possible to obtain an effect that strong light can be guided to the spectrophotometer with a simple device.

[0017] Also, other than the ignition timing of the normal, the expansion stroke or during the even during the exhaust stroke ignition circuit to analyze the composition of the gas to generate a spark in the spark plug, the fuel combustion in the internal combustion engine Since the feedback control is performed, the spark can be generated, for example, during the exhaust stroke or during the expansion stroke in addition to the normal ignition timing, so that the concentration of each gas component during those strokes can be known. In addition, there is an effect that finer combustion control can be performed.

[Brief description of the drawings]

FIG. 1 is a partial sectional view showing Embodiment 1 of the present invention.

FIG. 2 is a sectional view showing a second embodiment of the present invention.

FIG. 3 is a cross-sectional view showing a light detection unit of a conventional optical combustion control device.

[Explanation of symbols]

3 spark plug, 4 external electrode, 5 center electrode, 9 optical fiber, 10 light inlet, 11 spectrophotometer, 12
Optical fiber, 14 control circuit.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI H01T 13/40 F02P 17/00 H

Claims (1)

(57) [Claims] 1. A light guide opening penetrating a center electrode of a spark plug of an internal combustion engine, and a light inlet at a gap between the outer electrode and the center electrode of the spark plug. An optical fiber for guiding spark light generated at the time of ignition; a spectrophotometer connected to the optical fiber; and a control for analyzing a gas composition from an output of the spectrophotometer and performing feedback control on fuel combustion in the internal combustion engine. circuit and, and a firing circuit for supplying a high voltage to the spark plug, other than the normal ignition timing, during the expansion stroke or during the exhaust stroke
The above ignition circuit also produces a spark on the ignition plug
And analyze the gas composition to determine the fuel composition of the internal combustion engine.
Control device for feedback controlling fuel combustion.